To obtain high efficiency in a baseband power amplifier it is necessary to use switching techniques. A switching amplifier is known to produce switching noise. Prior art switching amplifiers have used passive filtering to reduce the switching noise. Such filtering limits the bandwidth of the amplifier, adversely affecting the slew rate and transient response time of the amplifier.
One method of reducing the switching noise without limiting the bandwidth more than an acceptable amount has been to increase the switching frequency. An undesirable side effect of increased switching frequency, however, is increased power consumption.
Thus, what is needed is an apparatus for providing a high bandwidth, low noise baseband amplifier which operates at a lower switching frequency than possible in prior art switching amplifiers.